Mauro Aparecido Martinez

Mobility of heavy metals as related to soil chemical and mineralogical characteristics of Brazilian soils

In order to better understand the relationship between soil characteristics and mobility of some heavy metals, correlation studies were conducted in samples of unlimed and limed A, B and C horizons of three Brazilian soils, representative of the majority of the tropical soils. A number of chemical and mineralogical characteristics of one Oxisol and two Ultisols were related to the retardation factors (Rf) for zinc (Zn), cadmium (Cd), copper (Cu) and lead (Pb). The retardation factors, obtained in leaching column experiments, were used as an estimate of solute movement in the profile. Soil types and soil horizons were found to influence metal retardation factors which, in turn, correlated better with the chemical than the mineralogical soil characteristics. For the unlimed soil samples, the soil characteristics that significantly correlated with Zn-Rf and Cd-Rf were the sum of exchangeable bases (SB), and soil exchangeable (Ca-KCl) and non-exchangeable (Ca-HCl) calcium contents. These results showed the strong influence of the cation exchange phenomenon on the retention and mobility of these two metals. For Cu and Pb, not only SB, cation exchange capacity (CEC) and Ca-KCl and Ca-HCl but also the organic matter correlated well with the Rf, showing that complex or chelate formation may play an important role in the movement of these elements. The important soil chemical characteristics related to the retardation factors in the limed soil samples were SB for Cd, and Ca-HCl for Cu and Pb, suggesting that precipitation may also influence the mobility and retention of the latter two heavy metals in these soil samples. Soil pH influenced the heavy metals adsorption and movement as shown by the significant correlation with the retardation factors when the combined data for the unlimed and limed soil samples was considered.

Influência da aplicação de águas residuárias de suinocultura na capacidade de infiltração de um solo Podzólico Vermelho-Amarelo

This work was carried out at the Experimental Area of Hydraulics, Irrigation and Drainage of the Agricultural Engineering Department, at the Federal University of Vicosa, Vicosa, Minas Gerais, Brazil. The aim was to evaluate the influence of successive applications of swine wastewater, with different concentrations of total solids, on the infiltration capacity of a Yellow Red Podzol. The experiment was conducted in a completely randomized design with five treatments and three replications. The treatments consisted of applying water and swine wastewater with 2.4, 7.0, 16.3 and 26.9 g L-1 of total solid concentrations. Fifteen ring infiltrometers were installed in an area of 60 m2, which was divided in plots of 2 x 2 m dimensions. Four infiltration tests were performed at 15 day intervals in each plot. It was concluded that increasing the total solid concentration of swine wastewater caused a reduction of the soil infiltration capacity. In addition, it was observed that successive applications intensified this effect. The total solid concentration of wastewater was more important to reduce the soil infiltration capacity than the levels of sodium absorption ratio and salinity.

Hydrological simulation using SWAT model in headwater basin in Southeast Brazil

Hydrological models are important tools that have been used in water resource planning and management. Thus, the aim of this work was to calibrate and validate in a daily time scale, the SWAT model (Soil and Water Assessment Tool) to the watershed of the Galo creek , located in Espirito Santo State. To conduct the study we used georeferenced maps of relief, soil type and use, in addition to historical daily time series of basin climate and flow. In modeling were used time series corresponding to the periods Jan 1, 1995 to Dec 31, 2000 and Jan 1, 2001 to Dec 20, 2003 for calibration and validation, respectively. Model performance evaluation was done using the Nash-Sutcliffe coefficient (ENS) and the percentage of bias (PBIAS). SWAT evaluation was also done in the simulation of the following hydrological variables: maximum and minimum annual daily flowsand minimum reference flows, Q90 and Q95, based on mean absolute error. ENS and PBIAS were, respectively, 0.65 and 7.2% and 0.70 and 14.1%, for calibration and validation, indicating a satisfactory performance for the model. SWAT adequately simulated minimum annual daily flow and the reference flows, Q90 and Q95; it was not suitable in the simulation of maximum annual daily flows.

Modelo numérico do transporte de nitrogênio no solo. Parte II: Reações biológicas durante a lixiviação

Analisar o efeito da temperatura e umidade do solo nos processos de mineralizacao e nitrificacao do nitrogenio e comparar as concentracoes de nitrato e amonio, simuladas pelo modelo SIMASS-C, com aquelas obtidas experimentalmente, foi o objetivo que norteou o presente trabalho, razao por que se conduziram dois experimentos, o primeiro em câmeras de incubacao, variando temperatura e teor de agua do solo, e um segundo, em colunas de lixiviacao montadas em laboratorio. A temperatura e a umidade afetaram as transformacoes de nitrogenio, cujos efeitos foram mais pronunciados a partir de 15 dias de incubacao, sobretudo nas temperaturas acima de 25 °C e umidades superiores a capacidade de campo. Ao se estimular as reacoes biologicas sofridas pelo nitrogenio, altos teores de agua no solo causaram maiores erros entre as concentracoes de nitrato e amonio simuladas e observadas.

Modeling of water infiltration in soil under stratified conditions using the Green-Ampt equation

Soil water infiltration is one of the most important processes of the hydrological cycle. The Green and Ampt equation (GA) is quite used to simulate the infiltration process, however, several authors showed the necessity of some adaptations in the GA parameters: saturation moisture (qs), hydraulic conductivity (K0) and mean suction in the wetting front (y). An evaluation was made of the GA model and of the several correction propositions of K0 and y, applied in a stratified Red-Yellow Latosol. A soil box filled with soil material belonging to three horizons of the studied soil was used. The accumulated infiltration (I), infiltration rate (Ti), as well as the physical characteristics of the profile needed for the application of the model were determined. Simulations based on the combination among six methodologies for the determination of y was made and three for the determination of hydraulic conductivity in the transmission zone (Kw). The following combinations simulated well the infiltration process: Kw equal to 0,5 K0 associated to y relative to the initial moisture content (y(qi)); Kw equals to the stable infiltration rate (Tie) associated to y equal to the mean among y (qi) and y relative to the saturation field moisture (y (qw)); Kw equal to K0 associated to y calculated with base in the texture and porosity of the soil and Kw equal to Tie associated to y calculated on the basis of texture and porosity of the soil.

Removal of Cu and Zn from swine raising wastewater using organic filters

Abstract Rice husks, coffee bean skins, sugar cane bagasse, maize cobs, saw dust and fine charcoal dust were evaluated as filters for the removal of heavy metals (Cu and Zn) from the waste water of swine raising installations. The specific mass, pH and the sum of bases and removable adds were determined to characterize each of the filter materials. Each filtering material was placed in a 100 mm diameter, 600 mm long, PVC column to a height of 500 mm under 12,500 N m‐2 of compression. Chemical and physical analyses were determined on effluent samples collected for each 1.5 l. up to a total of 15 l. The organic materials reduced the concentration of sediment solids (>90%), total solids (up to 33%) and Cu (up to 43.6%) of the inffluent but had little or no effect on Zn concentration.

Impacts of deforestation on water balance components of a watershed on the Brazilian East Coast

The Brazilian East coast was intensely affected by deforestation, which drastically cut back the original biome. The possible impacts of this process on water resources are still unknown. The purpose of this study was an evaluation of the impacts of deforestation on the main water balance components of the Galo creek watershed, in the State of Espirito Santo, on the East coast of Brazil. Considering the real conditions of the watershed, the SWAT model was calibrated with data from 1997 to 2000 and validated for the period between 2001 and 2003. The calibration and validation processes were evaluated by the Nash-Sutcliffe efficiency coefficient and by the statistical parameters (determination coefficient, slope coefficient and F test) of the regression model adjusted for estimated and measured flow data. After calibration and validation of the model, new simulations were carried out for three different land use scenarios: a scenario in compliance with the law (C1), assuming the preservation of PPAs (permanent preservation areas); an optimistic scenario (C2), which considers the watershed to be almost entirely covered by native vegetation; and a pessimistic scenario (C3), in which the watershed would be almost entirely covered by pasture. The scenarios C1, C2 and C3 represent a soil cover of native forest of 76, 97 and 0 %, respectively. The results were compared with the simulation, considering the real scenario (C0) with 54 % forest cover. The Nash-Sutcliffe coefficients were 0.65 and 0.70 for calibration and validation, respectively, indicating satisfactory results in the flow simulation. A mean reduction of 10 % of the native forest cover would cause a mean annual increase of approximately 11.5 mm in total runoff at the watershed outlet. Reforestation would ensure minimum flows in the dry period and regulate the maximum flow of the main watercourse of the watershed.

Substituição dos parâmetros do modelo de Green-Ampt-Mein-Larson para estimativa da infiltração em alguns solos do Brasil

Based on a detailed analysis of the process of water infiltration into the soil, an alternative is proposed to adjust the input parameters of the Green-Ampt-Mein-Larson (GAML) model to optimize infiltration estimates of some Brazilian soils. The adjustments consisted of the replacement of the parameters saturated hydraulic conductivity (K0) by stable infiltration rate (Tie) and soil moisture saturation (qs) by water content in the transmission zone (qw). Moreover, an equation was established to estimate the matric potencial at the wetting front (yf), based on the parameters of the water retention curve of Brooks and Corey. The performance of the set of proposed adjustments (GAML-t) was evaluated for the estimation of water infiltration in three soil types. The performance of GAML-t was compared with the original GAML and adjusted to five different situations. GAML-t performed best in the three soils under study.

Tifton grass yield on constructed wetland used for swine wastewater treatment

It is the purpose of this study to evaluate the agronomic behavior and yield of the Tifton 85 grass (Cynodon dactylon Pers), when used in the treatment of swine wastewater (SW) with constructed wetland systems (CWs). For this purpose, five tanks were built measuring 24 x 1.1 x 0.7 m, damp-sealed with PVC canvas and filled with 0.4 m crushed stone. In two of these tanks, Tifton grass was cultivated: one of the tanks (CW 3) contained the grass, and in the other (CW4) the grass was only cultivated in the final third part of the tanks, being preceded by Alternanthera (Althernanthera philoxeroides) and cattail (Thypha latifolia L.). The SW was previously treated by means of a filtration process that consists of 0.7 m - high organic filters; the filtering beds were made of chopped sugarcane bagasse. The filter effluents were applied to CWs at a 0.8 m3 d-1 flow rate, corresponding to a hydraulic detention time of about 4.8 days. During the experimental period, three cuttings were done in CWs plants in order to evaluate the dry matter yield and the nutrient extraction capacity. All plants showed satisfactory performance in dry mass yield (86.3 and 65.3 t ha-1, in CW3 and CW4 respectively) and nutrient extraction, as well as in dry matter yield. Except for the case of Zn, the cultivation of other vegetable species in the same tank did not alter the capacity of the Tifton 85 grass extraction of the SW macro and micronutrients removal.

Adequação dos parâmetros do modelo de Green-Ampt-Mein-Larson em condições de campo

Among the several equations that are proposed for simulation of infiltration, the Green-Ampt-Mein-Larson (GAML) model is one of the most used in hydrological studies as it is based on physical processes that occur in the soil during infiltration. However, some of its parameters do not match the real situation of the process of water infiltration in the soil. Thus, the objective of this work was to evaluate the performance of the GAML model, testing different methodologies for obtaining its parameters. The trials were carried out in a Podzol Tb Distrophic Haplic Cambisol, using a rain simulator, under field conditions, with and without mulch. Simulations were performed based on the combination of two methodologies for determination of soil water content in the transmission zone (θt), two for hydraulic conductivity in the transmission zone (θt) and three for the matric suction at the wetting front (ψf). The GAML model with its original parameters did not achieve good performance, overestimating the values of infiltration rate (Ti) and accumulated infiltration (I). Combinations using ψf values calculated by the equation of Risse et al. (1995) underestimated the whole time the values of Ti and I, under all surface conditions. The combination K0, θs and Cecilio (2005) equation showed the best results.